Disclosed herein are methods and apparatuses that provide for variable data density on a disc data storage medium, where the variable data density may have a circumferential definition and a radial definition. In some examples, devices and methods may include measuring a read or write performance attribute on a disc data storage medium and selectively setting a data density rate that may vary in a circumferential direction for the disc data storage medium based on the read or write performance attribute. In other examples, apparatuses can include a data storage device having a disc data storage medium and a controller configured to measure a performance attribute of the disc data storage medium and to selectively set different Bits Per Inch (BPI) for data storage within different areas of the disc.